Conventionally, various in-vehicle systems have been mounted in vehicles. For examples, JP 2000-104429A discloses a smart entry system as an example of these in-vehicle systems.
In recent years, in-vehicle systems have been increasingly complicated. To use an in-vehicle system, a user must memorize operation procedures by hearing an explanation from a dealer or reading a manual. If a user takes an erroneous operation procedure, the user is alerted by a buzzer or a display. Thereafter, however, the user must read a manual to cope with the alert.
As in-vehicle systems are complicated, manuals become voluminous. It is difficult to find the description of a desired operation procedure. To let a user know operation procedures, consequently, a voice guidance system is used to provide guidance about the operation procedures by voice. However, if this voice guidance is always outputted in a certain mode, a user who is already acquainted well with the operation procedures will be annoyed. It will also annoy surrounding people depending on the environment (time, location, noise) around the vehicle.